/* Copyright  (c) 2002 Graz University of Technology. All rights reserved.
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 *  
 * 3. The end-user documentation included with the redistribution, if any, must
 *    include the following acknowledgment:
 * 
 *    "This product includes software developed by IAIK of Graz University of
 *     Technology."
 * 
 *    Alternately, this acknowledgment may appear in the software itself, if 
 *    and wherever such third-party acknowledgments normally appear.
 *  
 * 4. The names "Graz University of Technology" and "IAIK of Graz University of
 *    Technology" must not be used to endorse or promote products derived from 
 *    this software without prior written permission.
 *  
 * 5. Products derived from this software may not be called 
 *    "IAIK PKCS Wrapper", nor may "IAIK" appear in their name, without prior 
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 *  THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
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 */

package iaik.pkcs.pkcs11;

import iaik.pkcs.pkcs11.wrapper.PKCS11Exception;



/**
 * Objects that implement this interface can be used in the InitializeArgs to
 * handle mutex functionality.
 *
 * @author <a href="mailto:Karl.Scheibelhofer@iaik.at"> Karl Scheibelhofer </a>
 * @version 1.0
 * @invariants
 */
public interface MutexHandler {

  /**
   * Create a new mutex object.
   *
   * @return The new mutex object.
   * @exception PKCS11Exception If the wrapper should return a differnet value
   *                            than CKR_OK to the library. It gets the
   *                            error-code and returns it as CK_RV.
   * @preconditions
   * @postconditions (result <> null)
   */
  public Object createMutex() throws PKCS11Exception;

  /**
   * Destroy a mutex object.
   *
   * @param mutex The mutex object to destroy.
   * @exception PKCS11Exception If the wrapper should return a differnet value
   *                            than CKR_OK to the library. It gets the
   *                            error-code and returns it as CK_RV.
   * @preconditions (mutex <> null)
   * @postconditions
   */
  public void destroyMutex(Object mutex) throws PKCS11Exception;

  /**
   * If this method is called on with a mutex object which is not locked, the
   * calling thread obtains a lock on that mutex object and returns.
   * If this method is called with a mutex object which is locked by some
   * thread other than the calling thread, the calling thread blocks and waits
   * for that mutex to be unlocked.
   * If this method is called with a a mutex object which is locked by the calling
   + thread, the behavior of this method call is undefined.
   *
   * @param mutex The mutex object to lock.
   * @exception PKCS11Exception If the wrapper should return a differnet value
   *                            than CKR_OK to the library. It gets the
   *                            error-code and returns it as CK_RV.
   * @preconditions (mutex <> null)
   * @postconditions
   */
  public void lockMutex(Object mutex) throws PKCS11Exception;

  /**
   * If this method is called with a mutex object which is locked by the
   * calling thread, that mutex object is unlocked and the function call
   * returns. Furthermore: If exactly one thread was blocking on that
   * particular mutex object, then that thread stops blocking, obtains a lock
   * on that mutex object, and its lockMutex(Object) call returns.
   * If more than one thread was blocking on that particular mutex objet, then
   * exactly one of the blocking threads is selected somehow. That lucky thread
   * stops blocking, obtains a lock on the mutex object, and its
   * lockMutex(Object) call returns. All other threads blocking on that
   * particular mutex object continue to block.
   * If this method is called with a mutex object which is not locked, then
   * the method call throws an exception with the error code
   * PKCS11Constants.CKR_MUTEX_NOT_LOCKED.
   * If this method is called with a mutex object which is locked by some
   * thread other than the calling thread, the behavior of this method call is
   * undefined.
   *
   * @param mutex The mutex object to unlock.
   * @exception PKCS11Exception If the wrapper should return a differnet value
   *                            than CKR_OK to the library. It gets the
   *                            error-code and returns it as CK_RV.
   * @preconditions (mutex <> null)
   * @postconditions
   */
  public void unlockMutex(Object mutex) throws PKCS11Exception;

}
